Cooling means for discharge lamps



Ap 7, 1942- v. J. FRANCIS ErAL COOLING MEANS FOR DISCHARGE LAMPS Filed Sept. 11, 1940 m5 am F O r I Se nmm e u a m P. 0 IT .m V.

Geor' y Their A1 forheg.

Patented Apr. 7, 1942 COOLING MEANS FOR DISCHARGELAMPS Yictor James 'Francis, North-:- Wembley, and George l-lulbert Wilson, Wembley Park, England, assignors to General Electric Company, a corporation of New York Application September 11, 1940, Serial No. 356,390

In Great Britain September 13, 1939 2 Claims.

Our invention relates to apparatus for produc ing light of the type wherein the source of light is a high-pressure metal-vapor electric discharge lamp subject to forced gas cooling in operation and wherein the leads to the electrodes of the lamp are carried in sealing stems projecting from the envelope of the lamp.

The lamps used in apparatus of this type usually have approximately spherical envelopes and are adapted in full operation to dissipate 1 kilowatt or more with a pressure of metal vapor within the envelope of 5 atmospheres or more.

tube 3 and is secured to it by means of extensions of the current leads 4 to anelectrode 5'of the lamp. The leads 4 consist of a plurality of thin metal strips, such as molybdenum strips, having tungsten wires fastened thereto. The leads 4 are arranged in spaced relation between an inner tube or cylinder of quartz and an outer quartz tube. These elements are fused together to form In such apparatus, of which optical projection apparatus is a typical example, it is often difiicult to arrange the forced gas cooling means so that it does not obstruct the light emitted from the lamp in the direction required and so that the lamp can be easily and accurately positioned relative to the rest of the apparatus. The object of this invention is to provide an arrangement in which the forced cooling means is adapted simul-' taneously to support and cool the lamp without unduly obstructing the light emitted from it and which enables the lamp to be easily and accurately positioned relative to the rest of the apparatus.

According to the invention in apparatus of the type specified the said forced cooling means com prises at least one hollow tube fitting over a sealing stem of the said HPMV lamp so that gas forced through the tube is directed over the envelope of the lamp, and the lamp is supported by the said sealing stem from the said tube or from a member supporting the said tube and is positioned relative to the rest of the apparatus by argon, at a pressure of about a centimeter and a quantity of mercury the vapor of which is lumin'osity producing during the operation of the a mechanically strong, as tight sealing stem. The external end of each of the leads 4 is clamped between the metaltube 3 and'the metal ring 6.

At its other end each tube 3 is connected by a flexible pipe I to a reservoir of compressed air (not shown) from which air is passed into the tube as indicated by the arrow; the air passes out of the tube 3 through orifices 8 and is directed over the envelope of the lamp by means oi:- a.

metal tube 9 which fits over the sealing stem 2 and is supported and insulated from the tube 3 by means of a rubber stopper H1;

The arrangement is supported, and the lamp thereby positioned relative .to the rest of the apparatus (not shown) by means of metal clamps ll supporting the tube 3. These tubes and the clamps ll act as extensions of the leads4 to the electrodes 5 and connections to the source .of electric supply (not shown) are taken from the arms I2 of the clamps.

It will be seen that in this embodiment each tube 9 is a said hollow. tube fitting over a sealing stem, each tube 3 is a said member supporting a said hollow tube and also the lamp, and each clamp H is a said means supporting a said tube or member as stated in the foregoing statement of invention.

In another embodiment of the invention the HPMV lamp is supported directly by its sealing stems from hollow tubes, such as 9 in the accompanying drawing, by means of rubber stoppers. Air is pressed through the tube by means of bores in the said stoppers and is directed by the tubes over the lamp. The arrangement is supported and the lamp positioned by means of clamps directly supporting the said tubes, and connections to the source of electric supply are taken directly from the leads emerging from the sealing stems.

lamp and has a vapor pressure of 5 atmospheres or more. Two elongated sealing stems 2 project from opposite sides of the envelope I. Each sealing stem abuts against one end of a hollow metal What we claim as new and desire to secure by Letters Patent of the United States is:

1. In combination, a high pressure gaseous electric discharge lamp of the type requiring forced cooling for proper operation and a'cooling system therefor, said lamp having a spherical envelope and elongated exposed stems projecting.

therefrom, said stems being mounted in opposing positions on said envelope, said cooling system comprising a metal tube removably fastened to one of said stems and another tube supported by said metal tube about said stem and said metal tube and terminating adjacent said envelope, the wall of said metal tube being perforated at the part thereof in said surrounding tube to permit the flow of cooling gas into said surrounding tube and directly over the surface of said stem and said envelope.

2. In combination, a high pressure gaseous electric discharge lamp of the type requiring forced cooling for proper" operation and a cooling system therefor, said lamp having a spherical enveiope and elongated exposed stems projecting therefrom, said stems being mounted in'opposing positions on said envelope, said cooling system comprising a metal tube removably fastened to one of said stems and another tube supported by said metal tube about said stem and said metal tube and terminating adjacent said envelope, the wall or said metal tube being perforated at the part thereof in said surrounding tube to permit the flow of cooling gas into said surrounding tube and directly over the surface of said stem and said envelope, said metal tube being a current lead for said lamp.

VICTOR JAMES FRANCIS. GEORGE HUL'BERT WILSON. 

